The present invention relates to initiators involved in controlling propellant-actuated devices (PADs) and, in particular, an initiator assembly having a circuit board with components to receive and process control signals to determine whether to activate such a device.
Inflators for inflating an air bag or other inflatable in a vehicle typically include an initiator assembly for igniting the propellant that is contained within the inflator housing. Upon activation of the propellant, it generates gases for filling the inflatable. The initiator assembly commonly includes an exterior configuration or member for connecting to a supporting structure. The assignee of the present application has previously developed an initiator assembly with an outer metal casing that has a collar for coupling to the inflator housing. The collar is located at the outer surface of insulating material that surrounds initiator conductive pins. In an initiator assembly design of another, it is known to injection mold portions of a cover with plastic material that surrounds portions of the initiator. The assignee of the present application has also developed an initiator assembly that facilitates a suitable connection between the initiator assembly and the inflator housing, while reducing the size of the injection molded part. Initiators have also been advanced that contain their own printed circuit board (PCB) including electronic components. The PCB processes control signals involved in the determination of whether or not to trigger or ignite the initiator.
Notwithstanding these previous disclosures, it is desirable to provide an initiator assembly that incorporates circuitry to receive and process a signal for use in determining whether to initiate at least one propellant actuated device, such as an automotive inflator, seat belt pretensioner, pin puller, cable cutter and/or gas generator. Due to the size of such circuitry, typically within the range of approximately 6-12 mm in diameter, incorporating such circuitry into an initiator assembly requires solutions to certain problems and consequences. For example, a typical initiator cap would not be large enough to house such circuitry. A larger initiator cap presents problems related to unwanted increased size and installation in the vehicle, in addition to the manufacturing cost for the initiator.
In accordance with the present invention, an initiator assembly is provided for use with devices that are activated when a propellant is ignited including an inflator, a seat belt pretensioner, a pin puller, a cable cutter and a gas generator. In the embodiment of an automotive inflator, the initiator assembly can comprise an initiator, circuitry and a collar assembly joined to the initiator. In another embodiment, the initiator assembly includes the initiator and the circuitry, but not the collar assembly. When activated by an ignition signal received by an initiator conductive pin and processed by the circuitry, the initiator assembly ignites the propellant contained in an inflator housing. In addition to at least one conductive pin, the initiator has a cap member that surrounds a charge that ignites when the circuitry receives a signal and determines to send the ignition signal. When present or being included, the collar assembly holds the initiator assembly to the inflator housing including after activation of the initiator.
The collar assembly includes an injected molded insulating material and an insert member that is fixedly joined to the insulating material during the injection molding process. The insert member can be configured according to a number of different embodiments, any one of which can be readily connected to an inflator housing by injection molding with the insulating material. The assignee of the present invention has previously developed such insert members and has filed application Ser. No. 09/044,523 entitled xe2x80x9cInflator Initiator With Insert Memberxe2x80x9d relating thereto and which is hereby incorporated by reference. At least one of the embodiments of the insert member is part of an initiator assembly that has a single conductive pin. However, other embodiments can be employed that have more than one such conductive pin.
The circuitry is capable of receiving and processing a control signal to determine whether to send an ignition signal to the initiator. The circuitry may be configured in many embodiments and may be positioned in a variety of locations within the initiator assembly, including on either side of the insert member. The circuitry may be electrically insulated by proper positioning of the circuitry within the initiator assembly before injection molding the insulating material. The circuitry is also properly protected against the high temperature(s) and pressure(s) that the electronic components can be subjected to during the injection molding process. This protection can include a protective coating or cover surrounding the circuitry that is provided before it is injection molded to the initiator. The circuitry may also contain one or more pass through ports or other connection(s) for a conductive pin. Importantly, the circuitry can be utilized with currently sized and available initiators.
Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings.